Update TbRelationalColumn.php

We should no use ',' to seprate multiple primary keys, because in that case $('#relatedinfo' + rowid) will always return []
add new TbJsonToggleColumn widget
removed comments
added comment about changes on changelog
fix CHANGELOG info line
Corrected CONTRIBUTING file to correspond to current state of things.
Merge pull request #660 from tamvodopad/tbjsontogglecolumnwidget

add new TbJsonToggleColumn widget
Merge branch 'master' of github.com:clevertech/YiiBooster
Merge pull request #654 from lixinqi/patch-1

Update TbRelationalColumn.php
Merge branch 'master' of github.com:clevertech/YiiBooster
Moved record about TbJsonToggleColumn to top of `CHANGELOG`.
Small changes to code style and fixed the incorrect getting of the name of `CActiveDataProvider.keyAttribute` inside `TbRelationalColumn`.
fix #659
fix clevertech/YiiBoilerplate#66
Small changes to code style and fixed the incorrect getting of the name of `CActiveDataProvider.keyAttribute` inside `TbRelationalColumn`.
fix #659
fix clevertech/YiiBoilerplate#66
Updated assets of `TbWizard`. Changed `minifyCss` to `minify` as it's for minifying *all* assets, not only CSS.
closes #645
Added latest changes to CHANGELOG
re #659 re #652 re #645
Small documentation and code style corrections.
Moved all assets of `TbJsonGridView` to packages.
Reformatted the custom YiiBooster CSS overrides.
Added notice about "minifyCss -> minify" change to CHANGELOG.md
Now you can create `TbSelect2` widget without any data and placeholder is being handled correctly for empty dropdowns.
fixes #247